1. Field of the Invention
The present invention relates to a magnetic tape cassette particularly suitable for use in magnetic recording and/or reproducing apparatus such as video tape recorders.
2. Description of the Prior Art
In general, magnetic tape cassettes of the type concerned include a housing composed of an upper shell and a lower shell assembled together to contain a length of a magnetic tape wound on a pair of reels. The magnetic tape is protected by a guard panel except when the tape cassette is loaded in a magnetic recording and/or reproducing apparatus such as a video tape recorder. One such known magnetic tape cassette is disclosed in Japanese Patent Laid-open Publication No. 59-168979.
The disclosed tape cassette includes a front lid and a rear lid normally disposed on opposite sides of a segment of the magnetic tape extending across the front side of the tape cassette, so as to enclose and thereby protect the magnetic tape against damage. The rear lid is integrally formed with a generally T-shaped top cover and includes a pair of pivot pins connected to the front lid, a pair of support arms and a pair of guide pins formed on the support arms, respectively, for pivotal movement of the rear lid relative to the tape cassette. The rear lid thus constructed has a complicated configuration. In addition, the lower shell has a pair of guide grooves in which the guide pins on the rear lid are slidably received.
The front and rear lids are pivotally movable between a closed position in which they enclose the magnetic tape in the manner described above, and an open position in which they are superposed one upon another on the upper shell. With this superposed arrangement, the maximum operational height of the tape cassette (namely, the distance from the under surface of the lower shell to a highest part of the front lid) is 1.5 times as large as the distance between the under surface of the lower shell and the upper surface of the upper shell. The tape cassette having such a large operational height is disadvantageous because a higher video tape recorder is needed.
When the front and rear lids are disposed in the closed position, the front lid is locked in position against displacement by a lock lever resiliently urged by a torsion coil spring. When the tape cassette is loaded in the video tape recorder, an unlock member abuts against a releasing projection on the lock lever to turn the lock lever against the force of the torsion coil spring, thereby unlocking the front lid. At the same time, a lid opening member lifts the front lid up until the front lid and the rear lid connected thereto turn in an open direction through an angle of about 90 degrees against the force of the torsion coil spring, thereby opening a front recessed portion or mouth across which a segment of the magnetic tape extends.
The lock lever and the torsion coil spring, which are provided to lock the front and rear lids in the closed position against accidental exposure of the magnetic tape, increase the number of structural components of the tape cassette and make a lid locking mechanism complicated in construction.